GLD(9F) Kernel Functions for Drivers GLD(9F)


gld, gld_mac_alloc, gld_mac_free, gld_register, gld_unregister, gld_recv,
gld_sched, gld_intr - Generic LAN Driver service routines


#include <sys/gld.h>

gld_mac_info_t *gld_mac_alloc(dev_info_t *dip);

void gld_mac_free(gld_mac_info_t *macinfo);

int gld_register(dev_info_t *dip, char *name, gld_mac_info_t *macinfo);

int gld_unregister(gld_mac_info_t *macinfo);

void gld_recv(gld_mac_info_t *macinfo, mblk_t *mp);

void gld_sched(gld_mac_info_t *macinfo);

uint_t gld_intr(caddr_t);

void gld_linkstate(gld_mac_info_t *macinfo, int32_t newstate);


illumos architecture specific (illumos DDI).


Pointer to a gld_mac_info(9S) structure.

Pointer to dev_info structure.

Device interface name.

Pointer to a message block containing a received packet.

Media link state.


gld_mac_alloc() allocates a new gld_mac_info(9S) structure and returns a
pointer to it. Some of the GLD-private elements of the structure may be
initialized before gld_mac_alloc() returns; all other elements are
initialized to zero. The device driver must initialize some structure
members, as described in gld_mac_info(9S), before passing the mac_info
pointer to gld_register().

gld_mac_free() frees a gld_mac_info(9S) structure previously allocated by

gld_register() is called from the device driver's attach(9E) routine, and
is used to link the GLD-based device driver with the GLD framework.
Before calling gld_register() the device driver's attach(9E) routine must
first use gld_mac_alloc() to allocate a gld_mac_info(9S) structure, and
initialize several of its structure elements. See gld_mac_info(9S) for
more information. A successful call to gld_register() performs the
following actions:

o links the device-specific driver with the GLD system;

o sets the device-specific driver's private data pointer (using
ddi_set_driver_private(9F)) to point to the macinfo structure;

o creates the minor device node.

The device interface name passed to gld_register() must exactly match the
name of the driver module as it exists in the filesystem.

The driver's attach(9E) routine should return DDI_SUCCESS if
gld_register() succeeds. If gld_register() returns DDI_FAILURE, the
attach(9E) routine should deallocate any resources it allocated before
calling gld_register() and then also return DDI_FAILURE.

gld_unregister() is called by the device driver's detach(9E) function,
and if successful, performs the following tasks:

o ensures the device's interrupts are stopped, calling the
driver's gldm_stop() routine if necessary;

o removes the minor device node;

o unlinks the device-specific driver from the GLD system.

If gld_unregister() returns DDI_SUCCESS, the detach(9E) routine should
deallocate any data structures allocated in the attach(9E) routine, using
gld_mac_free() to deallocate the macinfo structure, and return
DDI_SUCCESS. If gld_unregister() returns DDI_FAILURE, the driver's
detach(9E) routine must leave the device operational and return

gld_recv() is called by the driver's interrupt handler to pass a received
packet upstream. The driver must construct and pass a STREAMS M_DATA
message containing the raw packet. gld_recv() determines which STREAMS
queues, if any, should receive a copy of the packet, duplicating it if
necessary. It then formats a DL_UNITDATA_IND message, if required, and
passes the data up all appropriate streams.

The driver should avoid holding mutex or other locks during the call to
gld_recv(). In particular, locks that could be taken by a transmit thread
may not be held during a call to gld_recv(): the interrupt thread that
calls gld_recv() may in some cases carry out processing that includes
sending an outgoing packet, resulting in a call to the driver's
gldm_send() routine. If the gldm_send() routine were to try to acquire a
mutex being held by the gldm_intr() routine at the time it calls
gld_recv(), this could result in a panic due to recursive mutex entry.

gld_sched() is called by the device driver to reschedule stalled outbound
packets. Whenever the driver's gldm_send() routine has returned
GLD_NORESOURCES, the driver must later call gld_sched() to inform the GLD
framework that it should retry the packets that previously could not be
sent. gld_sched() should be called as soon as possible after resources
are again available, to ensure that GLD resumes passing outbound packets
to the driver's gldm_send() routine in a timely way. (If the driver's
gldm_stop() routine is called, the driver is absolved from this
obligation until it later again returns GLD_NORESOURCES from its
gldm_send() routine; however, extra calls to gld_sched() will not cause
incorrect operation.)

gld_intr() is GLD's main interrupt handler. Normally it is specified as
the interrupt routine in the device driver's call to ddi_add_intr(9F).
The argument to the interrupt handler (specified as int_handler_arg in
the call to ddi_add_intr(9F)) must be a pointer to the gld_mac_info(9S)
structure. gld_intr() will, when appropriate, call the device driver's
gldm_intr() function, passing that pointer to the gld_mac_info(9S)
structure. However, if the driver uses a high-level interrupt, it must
provide its own high-level interrupt handler, and trigger a soft
interrupt from within that. In this case, gld_intr() may be specified as
the soft interrupt handler in the call to ddi_add_softintr().

gld_linkstate() is called by the device driver to notify GLD of changes
in the media link state. The newstate argument should be set to one of
the following:

The media link is unavailable.

The media link is unavailable.

The status of the media link is unknown.

If a driver calls gld_linkstate(), it must also set the GLD_CAP_LINKSTATE
bit in the gldm_capabilities field of the gld_mac_info(9S) structure.


gld_mac_alloc() returns a pointer to a new gld_mac_info(9S) structure.

gld_register() and gld_unregister() return:

on success.

on failure.

gld_intr() returns a value appropriate for an interrupt handler.


gld(4D), dlpi(4P), attach(9E), gld(9E), ddi_add_intr(9F),
gld_mac_info(9S), gld_stats(9S)

Writing Device Drivers

February 15, 2020 GLD(9F)